1Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
In order to understand the capture characteristics of a trammel net for herded oval squid Sepioteuthis lessoniana, fishing method and catch composition were surveyed in Tateyama Bay, Chiba Prefecture, in 2002 and 2003. A trammel net with an inner mesh size of 85 mm and an outer mesh size of 360 mm was used in the fishing operation. The trammel net was operated for spawning-group of oval squid in an eelgrass bed area at a depth of 4-12 meters. The operation was divided into three stages: setting, herding and hauling. A total of 1,491 oval squid, 933 fish and 63 others were caught in 363 hauls. The discard rate based on the catch in number of the trammel net was estimated as 17 percent. The mean mantle length of oval squid was 28.0±5.8 cm. Oval squid smaller than 17 cm in mantle length were not captured by the trammel net. Oval squid were mostly taken in the central and bottom part of the trammel net, and 95 percent of the oval squid were pocketed by the bag-shaped inner net.